Shirley, who wrote and co-directed 2005’s wickedly clever zombie comedy “Hide and Creep,” has spent the past several years constructing “Interplanetary,” a no-budget sci-fi epic that relishes in the same brand of wry humor. His vision of a future on Mars is burdened with the sort of weight only the knowledge of a soul-sucking day job can provide: the Mars Base Two he creates is staffed not with astronauts, scientists, and heroes, but with management and support staff, the folks who have to check their company-provided binders to see what the policy is on every move. (Yup, Shirley even got those binders - those goddamn binders! - just right.)

Just imagine it: the brave future where space exploration is no longer a dream will eventually, inescapably reach the point when the all-too-ordinary get to take over. Shirley takes us beyond that point of first landing and shows us instead the moment when the person in charge has no idea how science works, and who sees a stint on Mars Base Two as just another crummy job, only this time there’s no Applebee’s to go to after work.

It helps that Shirley has cast his film with actors from his own corner of Alabama (including several familiar faces from “Creep”). There’s something about the accents (thick enough to be noticeable, thin enough to be completely natural and never distract) that pulls the rug out from everything we’ve ever come to expect about science fiction, space travel, and heroes.

Then again, Shirley doesn’t really provide us with heroes, either, at least not in the Joseph Campbell sense of the word. He’s too busy being blisteringly funny to bother with such simple ideas, and he’d rather have characters that sort of stumble into the story than burst into them. As with “Hide and Creep,” Shirley’s characters here specialize in a unique brand of mellow snark, a casual go-with-the-flow attitude (peppered with some of the cleverest dialogue you’ll ever hear in a genre flick) that makes even the jerkiest types a blast to watch.

Like in the opening scene, where Wil (Chuck Hartsell) and Ed (Nick Crawford) discover a Martian fossil, the first incontrovertible proof of extraterrestrial life (“A Martian fossil!” “I get that, because we’re on Mars.”); to Wil, that means only one thing: “We’re going to be knee-deep in money and hot women.” There’s someone else in that Martian cavern with them, but no heroics, just a bit of death peppered by dumb luck. And that’s sort of how the whole story progresses, as a string of stumbled-upon discoveries and, aside from those of a few noble (read: less idiotic) souls, misplaced priorities.

But who was that someone else? Does he have something to do with the strange radio signals mechanic Steve (Michael Shelton) discovered coming from nearby? Could that be Mars Base One, and if so, what’s going on over there? What does it have to do with the fossil? And hey, who’s the guy that shows up at the base door and starts shooting? Doesn’t he know how much paperwork is involved in that sort of thing? What does the manual say about exploded corpses? Do they require a lost-time accident report?

You can see where the comedy is headed. But Shirley and his cast are already a step ahead of you: rather than just make this “Office Space on Mars,” with oodles of “Dilbert”-grade cubicle jokes about corporate cluelessness (although they’re here, in spades - did I mention those goddamn binders?), “Interplanetary” goes a step further to create a believable scenario. The characters might be types - the bitchy boss, the obnoxious suck-up - but they’re not caricatures. How smart it is of Shirley to refuse to go broad with the jokes; it may be many things, but “Interplanetary” is never a parody. And in order to allow the comedy to come out of character, you have to build character, and Shirley takes his time doing just that, introducing us to this crappy, inescapable habitat, where, as grease monkey Beth (Mia Frost) puts it, “the only thing more boring than working is a day off.” (The most convincing element here is how bored everyone is by sex. They’ve all done it so often as a time-killer that it’s lost its appeal; in one scene, a character scoffs at an offer, preferring instead to cherish the planet’s last box of cheese puffs.)

For a comedy about life (and death) on Mars, it’s fun to see such attention paid to the little details. Watch in one scene as pissed-off cook Jackson (Kyle Holman), stuck being the film’s de facto hero since he’s the only one who knows how to handle a gun, casually helps save Steve from leaky spacesuit-caused certain death with a bit of Fix-a-Flat. It’s a throwaway moment, dependent entirely on the dismissive nature Jackson gives to Steve’s freak-out. Holman’s terrific here (and elsewhere, too), pausing just a bit to read the directions on the can and make sure his hunch is right. Things don’t like that usually happen in the movies, but they happen here, in a movie filled with pitch-perfect asides.

But the asides have to be perfect, if Shirley wants to pull off his ballsiest plan, to film the entire thing in good ol’ fashioned analog. There’s not a drop of CG effects or digital tweaking here; “Interplanetary” was shot entirely on 16mm film, all effects are the result of practical, on-set tricks, and every piece of scenery was built from scratch - all on a half-a-shoestring budget. It’s a hell of a risk, but it pays off: the film endears itself to us by looking homemade but never, ever cheap. The set design is genuinely gorgeous, as are the costumes, these wonderfully crafted spacesuits with bubble helmets straight out of old school sci-fi magazine covers. The low-tech look of the thing doesn’t just draw us in (although some of you will giggle with delight over such added side details as the 80s-level computer graphics seen in the backgrounds, or the all-too-visible cigarette burns included for reel changes, or the bastardized version of the Embassy Pictures logo used at the film’s open), it convinces us, completely, to root for Shirley and company. By the time a Martian monster shows up in full rubber-suit glory, we cheer. They actually pulled it off, the crazy bastards.

Even the music is retro. Eric McGinty and Ted Speaker take a cue from Shirley’s obvious John Carpenter influences and deliver a masterpiece of film scoring, filling the soundtrack with crunchy guitar and cheesy synths, enough to make you think Kurt Russell will walk into frame any minute now.

The whole film is very smart about being lo-fi. It knows its limitations but does not surrender to them; it relishes in creature feature silliness without losing sight of sharp writing and solid performances; it knows how to be fun without merely making fun of itself. Shirley is unquestionably one of the best outside-the-loop filmmakers working today, and “Interplanetary” is what all B-movies should want to be: audacious, intelligent, and start-to-finish entertaining, a slice of genius standing in bold defiance of the budget.